Neuromodulation is a method of treating pain symptoms by therapeutically altering activity in pain pathways with the use of an implantable device. Neuromodulation works by either actively stimulating nerves to produce a natural biological response or by applying targeted pharmaceutical agents in small doses directly to a site of action.
Electrical stimulation involves the application of electrodes to the brain, the spinal cord or peripheral nerves of a patient. These precisely placed electrodes are typically mounted on a lead that is connected to a pulse generator and power source, which generates the necessary electrical stimulation. A low-voltage electrical current passes from the generator to the nerve, and can either inhibit pain signals or stimulate neural impulses where they were previously absent.
In the case of pharmacological agents delivered through implanted leads or catheters, the drug can be administered in smaller doses because it does not have to be metabolized and pass through the body before reaching the target area. Smaller doses—in the range of 1/300 of an oral dose—can mean fewer side effects, increased patient comfort and improved quality of life.
However, neuromodulation is not without its risks and complications. Many studies show that less than 50% of patients receive meaningful pain relief with spinal cord stimulation. Patients fail spinal cord stimulation for many reasons including unwanted stimulation, inability to stimulate the target area, and sometimes loss of stimulation over time. Likewise, unpleasant stimulation of the chest or rib area may occur due to undesirable positioning or movement of the stimulation lead. In addition, changes in stimulation may occur over time due to scar tissue forming around the leads, fracture of the lead, or movement of the lead position. For example, migration of the electrode may occur resulting in a loss or change of stimulation.
Many of these complications may be lessened or avoided with more desirable placement of the stimulation leads and a greater ability to maintain electrodes in such desirable position. In addition, surgical complications may be lessened or reduced with less invasive procedures. Further, such positioning of leads should be reversible without damaging or harming the patient anatomy, particularly delicate nerve tissue. Currently, approximately 20% to 40% of conventional spinal cord stimulation patients require revision or explantation of at least one lead. Therefore, such positioning should be reversible in the instance that removal or repositioning of a lead is desired for any reason. At least some of these objectives will be met by the present invention.